A preliminary analysis of long-term self-reported sleep disturbance attributed to wind turbines and modelled outdoor nightly average wind turbine sound pressure level

The World Health Organization (WHO) Environmental Noise Guidelines provide source-based annual average nighttime sound pressure level (Lnight) recommendations. For non-aircraft sources the recommendation for self-reported high sleep disturbance (HSD) is the Lnight associated with an absolute prevalence of 3%HSD. The Guideline Development Group (GDG) reported that no Lnight recommendation could be provided for wind turbines because the evidence available was inadequate. In the current study, outdoor wind turbine Lnight at each dwelling was calculated following international standards. Questionnaires were completed between May and September 2013 by individuals aged 18-79y (606 males, 632 females), randomly selected from households 0.25 to 11.22 kilometers from operational wind turbines. Calculated Lnight ranged from <25 dB(A) to 46 dB(A). When the source of sleep disturbance was unspecified, the mean prevalence of HSD was 13.3% overall and unrelated to Lnight (p = 0.53). As Lnight increased, the prevalence of identifying wind turbines as one of the causes of sleep disturbance increased from 0% below 25 dB(A) to 3.8% (95% CI 1.9% to 7.4%) between 40-46 dB(A) (p = 0.01) . The WHO's 3%HSD threshold was estimated to occur for wind turbine Lnight between 38-39 dB(A).